Dakotaraptor is the last giant raptors and one of the few rivals of the T-rex. This predator hunts only fast prey such as ornithomimus and young hadrosaurs but could chase larger prey when hunting in pack. This raptor is definitely not a threat to adult t-rex but it might well kill youngster teens if the opportunity presents itself. Unlike the Utahraptor, the Dakotaraptor seems to be better built for speed and endurance.
(In fact, I suspected that the raptor presented in "Dinosaurs Decoded" is a Dakotaraptor).